Some 50 per cent of seven-year-old school children are not getting enough exercise.
Research carried out by University College London has found youngsters are sedentary for between six and seven hours a day and are failing to take the recommended level of one hour of moderate to vigorous physical activity.
It is the latest release from the Millennium Cohort Study and shows that girls are less active than boys. As no biological reasons can be found to explain this, scientists feel social factors - such as there not being enough girl-focused ball games in school playgrounds - are behind the issue.
Children of Indian ethnic origin and those living in Northern Ireland were found to be the least active.
Almost 7,000 UK school children were monitored for a week using an accelerometer, which is a device attached to an elastic band that measures how much exercise a kid does and what intensity it is. The equipment showed youngsters take an average of 10,299 steps every day.
Carol Dezateux, professor of paediatric epidemiology at the UCL Institute of Child Health, said: "What we need to see is a positive attitude to offering choice, diversity of opportunity, a wide range of activities and inclusiveness for all children - especially girls."
Of course, teachers have a vital role to play when it comes to encouraging children to exercise regularly. Schools need to stress how important being active is from the day youngsters walk through the doors.
According to the authors of the report, UK children are "insufficiently active" and so any chance to build on the legacy of the London Olympics is being wasted. They suggested more needs to be done to encourage young people to embrace exercise.
The north-west (58 per cent) was found to be the region best at making sure children carried out 60 minutes of intense physical activity a day, while the Midlands (46 per cent) fared the worst.
Posted by Tim Coleman